Pelagic primary production during summer along 65 to 72°N off West Greenland

The distribution of phytoplankton biomass and primary production were studied during summer 1993 at 16 stations from 65 to 72°N off West Greenland, ranging more than 900 km. Hydrography, nutrients and chlorophyll a profiles revealed a significant change in structure from south to north. Nitrate was depleted in the euphotic zone at most stations except close to the ice edge (West Ice) or close to outflow from large glaciers. The vertical distribution of phosphate followed that of nitrate, but was never depleted. Despite two stations with relatively high surface concentrations, silica showed the same distribution as the other two nutrients. In the south, chlorophyll a concentration and primary production were lower than north of Disko Bay (69°N), associated with a well-mixed versus a salinity-generated stratification, respectively. In Vaigat, a high-production station was identified, (st. 910, 69°52′69N–51°30′61W) with a chlorophyll a concentration in the euphotic zone of >13 μg l⁻¹ and an area primary production of 3.2 g C m⁻² day⁻¹. This is seldom encountered in arctic waters and was presumably due to nutrient-rich melt-water originating from the Iluliíssat Glacier. The overall primary production for the studied area was 67–3207 mg C m⁻² day⁻¹ (mean ± SD=341± 743 mg C m⁻² day⁻¹), which is within the range of the few results published for West Greenland and eastern Canadian Arctic waters. Accepted: 24 October 1998     

Cumulative solar irradiance and potential large-scale sea ice algae distribution off East Antarctica (30°E–150°E)

We present a computational model of the large-scale cumulative light exposure of sea ice in the Southern Ocean off East Antarctica (30°E–150°E). The model uses remotely sensed or modelled sea ice concentration, snow depth over sea ice, and solar irradiance data, and tracks sea ice motion over the season of interest in order to calculate the cumulative exposure of the ice field to photosynthetically active radiation (PAR). Light is the limiting factor to sea ice algal growth over winter and early spring, and so the results have implications for the estimation of algal biomass in East Antarctica. The model results indicate that highly light-exposed ice is restricted to within a few degrees of the coast in the eastern part of the study region, but extends much further north in the 30°E–100°E sector. The relative influences of sea ice motion, solar flux, and snow depth variations on interannual variations in model predictions were evaluated. The model estimates of cumulative PAR were found to correlate with satellite estimates of subsequent open-water chlorophyll-a concentration, consistent with the notion that sea ice algae can provide inocula for phytoplankton blooms.     

Vegetation recovery alters soil N status in subtropical karst plateau area: Evidence from natural abundance δ15N and δ18O

Plant and Soil - Forest recovery from disturbance can alter soil nitrogen (N) status as a result of complex interactions in plant-soil system. The δ15N and δ18O are indicators that...     

Diversity of Meiofauna from the 9°50′N East Pacific Rise across a Gradient of Hydrothermal Fluid Emissions

Background

We studied the meiofauna community at deep-sea hydrothermal vents along a gradient of vent fluid emissions in the axial summit trought (AST) of the East Pacific Rise 9°50′N region. The gradient ranged from extreme high temperatures, high sulfide concentrations, and low pH at sulfide chimneys to ambient deep-sea water conditions on bare basalt. We explore meiofauna diversity and abundance, and discuss its possible underlying ecological and evolutionary processes.

Methodology/Principal Findings

After sampling in five physico-chemically different habitats, the meiofauna was sorted, counted and classified. Abundances were low at all sites. A total of 52 species were identified at vent habitats. The vent community was dominated by hard substrate generalists that also lived on bare basalt at ambient deep-sea temperature in the axial summit trough (AST generalists). Some vent species were restricted to a specific vent habitat (vent specialists), but others occurred over a wide range of physico-chemical conditions (vent generalists). Additionally, 35 species were only found on cold bare basalt (basalt specialists). At vent sites, species richness and diversity clearly increased with decreasing influence of vent fluid emissions from extreme flow sulfide chimney (no fauna), high flow pompei worm (S: 4–7, H''_loge: 0.11–0.45), vigorous flow tubeworm (S: 8–23; H''_loge: 0.44–2.00) to low flow mussel habitats (S: 28–31; H''_loge: 2.34–2.60).

Conclusions/Significance

Our data suggest that with increasing temperature and toxic hydrogen sulfide concentrations and increasing amplitude of variation of these factors, fewer species are able to cope with these extreme conditions. This results in less diverse communities in more extreme habitats. The finding of many species being present at sites with and without vent fluid emissions points to a non endemic deep-sea hydrothermal vent meiofaunal community. This is in contrast to a mostly endemic macrofauna but similar to what is known for meiofauna from shallow-water vents.     

Vertical distribution of bacterial and archaeal communities along discrete layers of a deep-sea cold sediment sample at the East Pacific Rise (∼13°N)

The community structure and vertical distribution of prokaryotes in a deep-sea (ca. 3,191 m) cold sediment sample (ca. 43 cm long) collected at the East Pacific Rise (EPR) approximately 13 degrees N were studied with 16SrDNA-based molecular analyses. Total community DNA was extracted from each of four discrete layers EPRDS-1, -2, -3 and -4 (from top to bottom) and 16S rDNA were amplified by PCR. Cluster analysis of DGGE profiles revealed that the bacterial communities shifted sharply between EPRDS-1 and EPRDS-2 in similarity coefficient at merely 49%. Twenty-three sequences retrieved from DGGE bands fell into 11 groups based on BLAST and bootstrap analysis. The dominant groups in the bacterial communities were Chloroflexi, Gamma proteobacteria, Actinobacterium and unidentified bacteria, with their corresponding percentages varying along discrete layers. Pairwise Fst (F-statistics) values between the archaeal clone libraries indicated that the archaeal communities changed distinctly between EPRDS-2 and EPRDS-3. Sequences from the archaeal libraries were divided to eight groups. Crenarchaea Marine Group I (MGI) was prevalent in EPRDS-1 at 83%, while Uncultured Crenarchaea group II B (UCII B) abounded in EPRDS-4 at 61%. Our results revealed that the vertically stratified distribution of prokaryotic communities might be in response to the geochemical settings and suggested that the sampling area was influenced by hydrothermalism. The copresence of members related to hydrothermalism and cold deep-sea environments in the microbial community indicated that the area might be a transitional region from hydrothermal vents to cold deep-sea sediments.     

Comparative growth ecology of Ascophyllum nodosum from Norway (lat. 63°N) and Wales (LAT. 53°N)

Two populations of Ascophyllum nodosum (L.) Le Jol., one from Menai Bridge, Wales, other from Trondheim, Norway, were grown in Trondheim under identical conditions. The two populations showed an equal growth response to light (saturation at 100 Wm⁻² at a day-length > 18 h). Temperature optima were 17–18°C and 16°C for the Menai Bridge and Trondheim populations, respectively.In Menai Bridge, local apical growth during April–August was about twice that in Trondheim. When the two populations were exposed to identical conditions (natural light, variable irradiances, different daylengths, different temperatures), the Menai Bridge population had about a 40% better growth rate than the Trondheim population, irrespective of treatment. It is concluded that the differences in local growth rates are partly due to environmental conditions and partly to different genetic growth capacities.     

The vegetation history of a coastal stone-age and iron-age settlement at 70°N,Norway

The Holocene vegetation history of the islet of Melkøya at Hammerfest, Norway (70°42N, 23°36E) is documented by several pollen profiles sampled close to excavated stone-age and iron-age settlements. Local paludification began c. 9700 cal B.P. and oligotrophication from c. 7300 cal B.P. onwards. A Betula pubescens—B.nana heath/woodland persisted until c. 8500 cal B.P., when a mixed Betula pubescens—Pinus sylvestris forest developed. Development towards an open heath is recorded from c. 4700 cal B.P. and culminates around 2700 cal B.P. A weak, possibly anthropogenic, impact is recognisable from c. 9200 cal. BP, but a marked local impact by man begins with the climate improvement and local forest development around 8500 cal B.P. The anthropogenic impact on the vegetation was the cutting of local woodland with an increase in grasses and herbs, the latter partly originating from the nitrophilous seashore vegetation. Forest clearance is recognisable at c. 6200 cal B.P., following a short period of re-growth after a burning event. Several anthropogenically related charred layers were formed in the peat before a longer period of abandonment from c. 3100 cal B.P. to c. 2000 cal B.P.     

Spatio-temporal variability of ichthyoplankton and its relationship with oceanographic conditions at the shelf break off Chilean Patagonia (43°S–51°S)

Larval fish composition and abundance have been studied in fjords of south Patagonia. However, the ichthyoplankton of the adjacent shelf and slope waters of the Pacific Ocean, which is an important spawning and nursery ground for demersal fishery species (e.g. austral hake and Patagonian grenadier), remains largely unknown. To compare ichthyoplankton occurrence with environmental conditions in August 2013 and 2014 (austral winter), two bio-oceanographic cruises were carried out between 43° and 51°S. Conductivity, temperature and depth (CTD) data and ichthyoplankton samples were collected. The highest frequency of occurrence (FO) was observed for eggs of lightfish Maurolicus parvipinnis (84 and 91% FO in 2013 and 2014, respectively) and larvae of the myctophid Lampanyctodes hectoris (60 and 94% FO, respectively). Ichthyoplankton composition and abundance varied significantly between years, and richness varied from 10 (2013) to 18 taxa (2014). Only larval L. hectoris showed a significant increase in abundance during the winter of 2014. Water column temperature and salinity were significantly different between years; the water was warmer and saltier in 2013. Canonical Correspondence Analysis detected positive relationships between temperature and salinity with egg abundance and larval distribution of Merluccius australis. The highest abundance of eggs of M. australis was found at ～6–10°C, mainly off south Guafo Island. Additionally, ichthyoplankton from the shelf-break area off south Patagonia showed a wider latitudinal distribution in the winter of 2014 than in 2013.     

Size and density of East Greenland polar bear (Ursus maritimus) skulls: Valuable bio-indicators of environmental changes?

There is an increasing interest in assessing the relationship between climatic oscillations, environmental contaminants and the modelling of animal physiological and morphological responses. We therefore undertook a study of skull condylobasal length (CBL; reflecting body size) and bone mineral density (BMD) in 87 East Greenland male polar bears (Ursus maritimus) sampled in the time period of 1892–2010. The purpose of the study was to investigate if these measures are potential candidates as indicators for stress associated with climate change and long-range transported toxic industrial chemicals. The analyses showed that both BMD and CBL in polar bears sampled in period 4 (1999–2010, n = 57) were significantly lower when compared with period 2 (1920–1936, n = 19) (both p < 0.02). Groups of persistent organohalogen contaminants (PCBs [polychlorinated biphenyls], DDT [dichlordiphenyltrichlorethane], HCH [hexachlorocyclohexane], HCB [hexachlorobenzene], chlordanes, dieldrin, PBDEs [polybrominated diphenyl ethers]) were measured in period 4 and multiple regression analyses controlling for age showed that dieldrin had a significant negative effect on BMD (p = 0.03, n = 52) while significant positive correlations with CBL were found for DDT, dieldrin and PBDE (all p < 0.05, n = 52). When testing the correlation with the North Atlantic Oscillation climate index no significant relationship was found for BMD (p = 0.97, r = −0.01, n = 27) nor CBL (p = 0.31, r = −0.2, n = 27). We therefore suggest that BMD and body size have decreased in East Greenland polar bear males over the past 120 years and that exposure to organohalogen contaminants may explain the BMD reductions. It is, however, not entirely clear if and how climatic oscillations affected the reductions in body size and BMD mainly because of the limited sample size in period 2 and lower mean age in period 4. Therefore, precautions should be taken towards a final conclusion on BMD and CBL as bioindicators for climate oscillations and exposure to toxic environmental chemicals. It is recommended that the sampling and archiving of East Greenland polar bear skulls continue in order to further explore how CBL and BMD reflect individual and population response upon exposure to environmental stress.     

Vitamins A and E in liver,kidney, and whole blood of East Greenland polar bears sampled 1994–2008: reference values and temporal trends

Vitamins A (retinol) and E (α-tocopherol) are dietary vitamins, essential for, e.g., growth and development, reproduction, and immune function. Persistent organic pollutants (POPs) have been found to be related to vitamin A and E metabolism. However, few investigations have been published on this health issue in polar bears (Ursus maritimus). The aim of this study was thus to provide reference values for concentrations of vitamin A in liver, kidney cortex, and whole blood and vitamin E in kidney cortex and whole blood from 166 East Greenland polar bears, as well as to assess the relationship between POPs and vitamin concentrations. In addition, vitamin concentrations were analyzed for temporal trends (1994–2008). Results showed vitamin A in liver to be higher in adult bears and the concentrations of vitamin E in kidney and blood to likewise be generally higher in adult bears. In addition, all analyzed contaminant groups were correlated with at least one of the vitamin parameters, predominantly in a negative way. Finally, vitamin A liver concentrations as well as concentration of vitamin E in kidney and blood showed a temporal increase. Together, these results add to the weight of evidence that POPs could be disrupting polar bear vitamin status. However, while the observed temporal increases in vitamin concentrations were likely POP related, the question remains as to whether they stem from influence of contaminants only or also, e.g., changes in prey species. Further studies are needed to tease apart the causes underlying these changes in vitamin concentrations.     

Distribution,abundance and biology of polar cod, <Emphasis Type="Italic">Boreogadus saida</Emphasis>, in Iceland–East Greenland waters

Recent warming has caused a northern extension in the distribution of many southern fish species in Icelandic waters. Polar cod (Boreogadus saida) around Iceland are near the southern limit of their distribution, but are poorly studied in the area. Therefore, material sampled during demersal fish surveys in March 1985–2013 and in pelagic 0-group surveys in Iceland–East Greenland waters in August–September 1974–2003 was used to investigate their distribution, abundance and biology. Demersal polar cod were most often caught on the outer shelf to the north-west and north of Iceland, but during years of widest distribution and highest abundance, they were caught farther to the east on the northern shelf. Pelagic 0-group polar cod were only caught sporadically and mainly confined to the waters off the north-west shelf of Iceland and the East Greenland shelf (southern Denmark Strait). In demersal hauls, the number of stations with polar cod decreased with increasing bottom temperature and polar cod were most widely distributed in the years 1989, 1994 and 1995. Highest numbers of demersal polar cod per haul were caught at temperatures of ?0.5 to 2.5 °C and at 200–450 m depth. The length of demersal polar cod ranged from 5 to 32 cm, while the fish caught in the pelagic trawl ranged from 2.2 to 19 cm. The polar cod in the subarctic waters north of Iceland most likely originate from the waters off East Greenland and further warming and decline in sea ice may eventually lead to the disappearance of polar cod from Icelandic waters.     

Comparative antigenic proteins and proteomics of pathogenic Yersinia enterocolitica bio-serotypes 1B/O: 8 and 2/O: 9 cultured at 25°C and 37°C

Yersinia enterocolitica is a Gram-negative enteric pathogen responsible for a number of gastrointestinal disorders; the most pathogenic bio-serotype is 1B/O: 8. In this study, we compared the antigenicity of the outer membrane proteins and proteomics of the whole-cell proteins of a pathogenic bio-serotype 2/O: 9 isolated in China and a bio-serotype 1B/O: 8 strain isolated in Japan. Using two-dimensional gel electrophoresis, we showed that the outer membrane proteins A (OmpA), C (OmpC) and F (OmpF) were the major antigens for both strains, although proteins located on the bacterial cell membrane and enzymes involved in energy metabolism were also identified as antigenic. We compared the whole-cell proteins of the two strains cultured at 25°C and 37°C and found portions of the outer membrane proteins (OmpX, OmpF and OmpA) were downregulated when the bacteria were cultured at 37°C, whereas urease subunit gamma (UreA), urease subunit alpha (UreC) and urease accessory protein (UreE), which are involved in urease synthesis, were upregulated when the bacteria were grown at 37°C. These observations will lay a foundation to selection of diagnostic markers for pathogenic Yersinia enterocolitica, and maybe contribute to choose the vaccine targets.     

A thermally induced alteration in lysosome membranes: Salt permeability at 0 and 37 °C

Preparations of radioactive lysosomes were obtained from mouse kidney after injection of radioactive iodine-labeled bovine ribonuclease. Stability of these lysosomes in various media was estimated from measurements of proteolytic activity towards the ribonuclease, and of ribonuclease retention in particles. The lysosomes were stable at 37 °C in isotonic, sucrose-free solutions of KCl, NaCl and potassium acetate, and in mixtures of these with MgCl₂, showing that these salts are relatively impermeant through the lysosomal membranes. The membranes were less permeable to Na⁺ than to K⁺. Both KCl and NaCl exerted their optimal protective effects over a broad concentration range above 0.125 M in 0.025 M acetate buffer. Mg²⁺ enhanced the protective effect of both K⁺ and Na⁺; the osmotic effect of 0.075 M NaCl-0.05 M MgCl₂ was indistinguishable during the entire course of ribonuclease digestion from that of isotonic sucrose. Osmotic protection by KCl-MgCl₂ was demonstrated over the pH range 5.5–7.0. A marked alteration in membrane properties occurs at lower temperatures in 0.11 M KCl-0.01 M MgCl₂ such that, at 0 °C, K⁺ permeability is much higher than at 37 °C, as shown by a several-fold decrease in stability at the lower temperature.     

Activity and distribution of thermophilic prokaryotes in hydrothermal fluid, sulfidic structures, and sheaths of alvinellids (East Pacific Rise, 13°N)

Processes of inorganic carbon assimilation, methanogenesis, sulfate reduction, and acetate oxidation to CO(2) occurring in samples from the East Pacific Rise at 13°N were traced, using radioisotopically labeled substrates, at temperatures ranging from 65 to 100°C. Molecular hydrogen stimulated lithotrophic methanogenesis and sulfate reduction but inhibited inorganic carbon assimilation. Active mineralization of acetate was observed in an organic-rich Alvinella-associated system at 80°C. Members of the Thermococcales were the most numerous hyperthermophilic archaea in these samples, their density achieving 10(8) cells per cm(3), while the numbers of cultured hydrogen-utilizing thermophilic lithotrophs were several orders of magnitude lower.     

Invasion of sorghum seed by storage fungi at moisture contents of 13.5–15 % and condition of samples from commercial bins

In sorghum seed stored at 22–25° C for 535 days, invasion by storage fungi and loss of germinability increased greatly with small increases in moisture content between 13.5 and 15.5 %. Seeds dried for 18 hours at 70° C, then exposed to a relative humidity of 75 %, had a lower equilibrium moisture content, but were more heavily invaded by storage fungi and lost germinability fsater, than those that had been conditioned to 20 % moisture before storage at 75 % relative humidity. The 10 samples of Grade No. 2 sorghum examined averaged about 13.0 % moisture, germinated an average of 59 %, yieldedAlternaria from 75 % of the surface-disinfected kernels andAspergillus glaucus from 4 %; judged by these criteria, the lots from which the samples came were in good condition for continued storage.     

New methods and technologies for regional-scale abundance estimation of land-breeding marine animals: application to Adélie penguin populations in East Antarctica

Land-breeding marine animals such as penguins, flying seabirds and pinnipeds are important components of marine ecosystems, and their abundance has been used extensively as an indication of ecosystem status and change. Until recently, many efforts to measure and monitor abundance of these species’ groups have focussed on smaller populations and spatial scales, and efforts to account for perception bias and availability bias have been variable and often ad hoc. We describe a suite of new methods, technologies and estimation procedures for cost-effective, large-scale abundance estimation within a general estimation framework and illustrate their application on large Adélie penguin populations in two regions of East Antarctica. The methods include photographic sample counts, automated cameras for collecting availability data, and bootstrap estimation to adjust counts for the sampling fraction, perception bias, and availability bias, and are applicable for a range of land-breeding marine species. The methods will improve our ability to obtain population data over large spatial and population scales within tight logistic, environmental and time constraints. This first application of the methods has given new insights into the biases and uncertainties in abundance estimation for penguins and other land-breeding marine species. We provide guidelines for applying the methods in future surveys.